"This isn't about trade tariffs now, this is about a potential economic war," Mr Weston said.

"This is moving on from what was a trade tit-for-tat into something that could be much more far-reaching."

Markets are very skittish about an apparently rapid unravelling of the global, interconnected modern economic order and yet another tweet by Trump about how well trade talks are going won't be able to reassure them, Mr Weston added.

The global sell-off eclipsed the start of the last week of Australian earnings season.

Gold miners were the only bright spot as the price of the precious metal reached $US1542 an ounce, its highest price since April 2013.

Newcrest gained 4.6 per cent to $36.05, Northern Star climbed 8.7 per cent to $12.39, Evolution was up 9 per cent to $5.33 and Westgold shot up 20.2 per cent to a two-year high of $2.35.

Elsewhere in the materials sector, Boral fell 20.6 per cent to a six-year low of $3.94 after the building materials maker's underlying net profit slumped 7.0 per cent.

Mining giant BHP gained 2.1 per cent to $36.49, Rio Tinto was down 2.6 per cent to $82.78 and Fortescue Metals dropped 5.3 per cent to $7.17 despite the iron ore producer almost tripling its full-year profit.

The big four banks were all lower, with ANZ down 1.4 per cent to $26.27, Commonwealth down 0.8 per cent to $76.76, NAB down 1.0 per cent to $27.06 and Westpac down 0.7 per cent to $27.62.

Macquarie fell 2.2 per cent and IOOF fell 6.9 per cent after it set aside another $235 million for customer remediation.

Amaysim plunged 23 per cent to an all-time low of 51.5 cents after the mobile and energy plan provider said its full-year underlying earnings had dropped by a third.

G8 Education fell 16 per cent to a 10-month low of $2.30 after reporting a mixed performance at its recently acquired childcare centres.

Adairs gained 11.8 per cent to a two-month high of $1.755 after the homeware company reported its full-year sales grew 9.7 per cent.

The Aussie dollar is buying 67.50 US cents, from 67.53 US cents on Friday.

ON THE ASX

* The benchmark S&P/ASX200 index closed down 83 points, or 1.27 per cent, to 6,440.1

* The All Ordinaries closed down 83.3 points, or 1.26 per cent, to 6,531.

* The SPI200 futures index closed up 28 points, or 0.45 per cent, to 6,183.